(1) Field of the Invention
The present invention relates to a jet mill in which crushed material introduced into a crushing chamber is comminuted by a swirl flow produced by a gas sprayed from a plurality of spray nozzles disposed along an inner perimeter wall of the crushing chamber.
(2) Description of Related Art
Jet mills pulverize and comminute crushed material introduced into a crushing chamber by a swirl flow from high-speed jets, and are useful in producing pesticides, toners, and other powders having poor heat resistance; ceramic powders; and a variety of other fine powders.
FIGS. 17 and 18 show schematic configurations of a conventional jet mill. FIG. 17 schematically shows a sectional configuration viewed from the side, and FIG. 18 schematically shows a cross section of the principal component thereof.
A jet mill 10′ shown in the stated drawings is equipped with a plurality of gas-jet nozzles 20, 21 in a housing 11 that forms a crushing chamber 12. Each of the jet nozzles 20, 21 is fixed in place so that the spraying orifice belonging thereto faces a prescribed direction within the crushing chamber 12.
In the example shown in the stated drawings, one nozzle (20) among the plurality of gas-jet nozzles 20, 21 is formed as a solid-gas mixing ejector nozzle for feeding crushed material into the crushing chamber 12. The ejector nozzle (20) is used to introduce and spray crushed material fed from a hopper-shaped crushed material feed part 32 through a drive nozzle 31 along with a high-speed stream of gas.
High-pressure gas (air or another suitable gas) is fed into each of the gas-jet nozzles 20, 21 and the drive nozzle 31 via a gas feed tube 41 from a high-pressure actuating gas feed device 40. Crushed material introduced into the crushing chamber is drawn in, pulverized, and comminuted in the high-speed swirl flow generated by the gas sprayed from the plurality of gas-jet nozzles 20, 21 disposed along the inner perimeter wall of the crushing chamber 12. Comminuted powder is removed via a fine-powder discharge port 14 disposed above the central area of the crushing chamber 12.
An example of this type of jet mill is disclosed in Patent Document 1.    [Patent Document 1]    JP-B 3335312